1. Field of the Invention
The present invention relates to thin film magnetic heads for magnetic recording apparatus, such as audio visual apparatus, and a method of manufacturing the same, and particularly, to a thin film magnetic head with improved productivity, cost performance and tape running characteristics, and a method of manufacturing the same.
2. Description of the Background Art
Hereinafter, description will be made on a conventional method of manufacturing a thin film magnetic head with reference to FIGS. 9A to 9F and FIG. 10.
In a conventional method of manufacturing a thin film magnetic head, as shown in FIG. 9A, a layer to be a lower magnetic core layer 22, which is made of a soft magnetic thin film of Ni--Fe, Fe--Al--Si, Fe--Al--N, Co--Zr or the like having high saturation magnetization characteristics, is formed with a sputter method or the like on a wafer substrate 21 of crystallized glass, Mn--Zn ferrite or the like having excellent wear resistance. After patterning this layer in a prescribed configuration to form lower magnetic core layer 22, a magnetic gap 23 made of a mineral insulating layer of SiO.sub.2, Si.sub.3 N.sub.4, Al.sub.2 O.sub.3 or the like is formed on lower magnetic core layer 22 with a sputter method. A bias lead 30 and a magnetoresistive element (hereinafter referred to as "an MR element") 31 are formed and subjected to insulating coating. An upper magnetic core layer 24 is then formed in a prescribed configuration similarly to lower magnetic core layer 22, to form a structure shown in FIG. 9A.
As shown in FIG. 9B, a passivation film 25 of SiO.sub.2, Si.sub.3 N.sub.4, Al.sub.2 O.sub.3 or the like is formed on an element portion on the substrate excluding a wiring connection portion P with a sputter method, a plasma CVD (Chemical Vapor Deposition) method or the like.
Subsequently, a protruding portion of passivation film 25 on element portion S is planarized by flattening polishing (FIG. 9C). A Cr film is formed thereon as a contact layer by vapor deposition or a sputter method, and a protection plate 26 of Zn--ferrite, CaTiO.sub.3 or the like is attached with an epoxy family adhesive or the like (FIG. 9D).
Wafer substrate 21 on which a plurality of magnetic heads are formed is then cut, and subjected to cylindrical grinding and tape lapping, to form a magnetic tape sliding surface B with a prescribed gap depth (FIG. 9E). A flexible printed substrate 27 as a terminal wiring is connected to wiring connection portion P on substrate 21 by a known wire bonding method or a tape automatic bonding method (hereinafter referred to as TAB), and covered with a resin mold 28 (FIG. 9F).
The thin film magnetic head in a cut off tip is incorporated into a tape guide 29 with prescribed accuracy (FIG. 10), to form a thin film magnetic head unit shown in FIG. 11, where a magnetic recording medium 20 is sliding in contact with magnetic head sliding surface B.
While FIGS. 9A to 9F and FIG. 10 show the conventional manufacturing process of a magnetoresistance effect type thin film magnetic head having bias lead 30 and MR element 31, similar process can be applied to a magnetic induction type thin film magnetic head, except that a conductor coil is formed in place of bias lead 30 and MR element 31.
In the conventional manufacturing method of the thin film magnetic head described above, however, various and complicated steps are required for finishing a head unit after formation of element portion S on substrate 21, which brings about the following problems.
(i) In order to cover the step at element portion S completely, passivation film 25 of mineral material shown in FIG. 9B must be formed in the thickness of 10 to 20 .mu.m, which requires long time of 6 to 12 hours, even employing a plasma CVD method.
(ii) The difference of the polished amount in flattening polishing of passivation film 29 shown in FIG. 9C might be caused by an error in thickness, deformation of the substrate or the like, so that upper magnetic core layer 22 on element portion S would be partially exposed out of passivation film 25.
(iii) The magnetic tape sliding surface might be damaged by a crack at passivation film 25 caused by polishing of the magnetic tape sliding surface shown in FIG. 9E.
(iv) Protection plate 26 attached as shown in FIG. 9D might be displaced by thermal stress in connecting or molding the terminal wiring shown in FIG. 9F.
(v) Because of these disadvantageous events in (i) to (iv), the yield is decreased, and the production cost is increased.
In addition, wear of the tape sliding surface causes reduction of frequency characteristics and an error between tracks in a reproduced output. Enhancement of wear resistance of the magnetic head sliding surface is thus desired.